Normal tissue homeostasis is a highly regulated process of cell proliferation and cell death, and an imbalance of either cell proliferation or cell death can develop into a cancerous state (Solyanik et al., 1995; Stokke et al., 1997; Mumby and Walter, 1991; Natoli et al., 1998; Magi-Galluzzi et al., 1998). The maintenance of cell proliferation and cell death is at least partially regulated by proto-oncogenes. A proto-oncogene can encode proteins that induce cellular proliferation (e.g., sis, erbB, src, ras and myc), proteins that inhibit cellular proliferation (e.g., Rb, p53, NF1 and WT1) or proteins that regulate programmed cell death (e.g., bcl-2) (Ochi et al., 1998; Johnson and Hamdy, 1998; Liebermann et al., 1998). However, genetic rearrangements or mutations to these proto-oncogenes results in the conversion of a proto-oncogene into a potent cancer causing oncogene. Often, a single point mutation is enough to transform a proto-oncogene into an oncogene. For example, a point mutation in the p53 tumor suppressor protein results in the complete loss of wild-type p53 function (Vogelstein and Kinzler, 1992; Fulchi et al., 1998) and acquisition of “dominant” tumor promoting function.
Immunotherapy, a rapidly evolving area in cancer research, is one option for the treatment of certain types of cancers. For example, the immune system identifies tumor cells as being foreign and thus are targeted for destruction by the immune system. Unfortunately, the response typically is not sufficient to prevent most tumor growths. However, recently there has been a focus in the area of immunotherapy to develop methods that augment or supplement the natural defense mechanism of the immune system. Examples of immunotherapies currently under investigation or in use are immune adjuvants (e.g., Mycobacterium bovis, Plasmodium falciparum, dinitrochlorobenzene and aromatic compounds) (U.S. Pat. No. 5,801,005; U.S. Pat. No. 5,739,169; Hui and Hashimoto, 1998; Christodoulides et al., 1998); cytokine therapy (e.g., interferons α, β and γ; IL-1, GM-CSF and TNF) (Bukowski et al., 1998; Davidson et al., 1998; Hellstrand et al., 1998); gene therapy (e.g., TNF, IL-1, IL-2, p53) (Qin et al., 1998; Austin-Edward and Villaseca, 1998; U.S. Pat. No. 5,830,880 and U.S. Pat. No. 5,846,945); and monoclonal antibodies (e.g., anti-ganglioside GM2, anti-HER-2, anti-p 185) (Pietras et al., 1998; Hanibuchi et al., 1998; U.S. Pat. No. 5,824,311).
As mentioned above, proto-oncogenes play an important role in cancer biology. For example, Rb, p53, NF1 and WT1 tumor suppressors are essential for the maintenance of the non-tumorogenic phenotype of cells (reviewed by Soddu and Sacchi, 1998). Approximately 50% of all cancers have been found to be associated with mutations of the p53 gene, which result in the loss of p53 tumor suppressor properties (Levine et al., 1991; Vogelstein and Kinzler, 1992; Hartmann et al., 1996a; Hartmann et al., 1996b). Mutations in the p53 gene also result in the prolongation of the p53 half-life in cells and the overexpression of p53 protein. In normal cells, p53 is undetectable due to its high turnover rate. Thus, p53 overexpression in cancerous cells results in multiple immunogenic p53 epitopes that can be used in immunotherapy. The high incidence of cancer related to mutations of the p53 gene has prompted many research groups to investigate p53 as a route of cancer treatment via gene replacement. The proto-oncogenes sis, erbB, src, ras and myc, encoding proteins that induce cellular proliferation, and the proto-oncogenes of the Bcl-2 family that regulate programmed cell death also play important roles in the non-tumorogenic phenotype of cells.
A few also have explored the use of p53 in immunotherapy. For example, in an in vitro assay, p53 mutant peptides capable of binding to HLA-A2.1 and inducing primary cytotoxic T lymphocyte (CTL) responses were identified (Houbiers et al., 1993). In a study in which synthetic p53 mutant and wild-type peptides were screened for immunogenicity in mice, it was observed that only mutant p53 epitopes were capable of eliciting a CTL response (Bertholet et al., 1997). In contrast, the immunization of BALB/c mice with bone marrow-derived dendritic cells (DC) in the presence of GM-CSF/IL-4 and prepulsed with the H-2Kd binding wild-type p53 peptide (232-240) was observed to induce p53 anti-peptide CTL response (Ciemik et al., 1996; Gabrilovich et al., 1996; Yanuck et al., 1993; DeLeo, 1998; Mayordomo et al., 1996). Further, the intradermal and intramuscular injection of naked plasmid DNA encoding human wild-type p53 and the intravenous injection of human wild-type p53 presented by a recombinant canarypox vector have been successful in the destruction of tumors (Hurpin et al., 1998).
Pre-clinical studies using mouse models (Ishida et al., 1999; Murakami et al., 2004; Espenschied et al., 2003; Blaszczyk-Thurin et al., 2002; Cicinnati et al., 2005) and an ex vivo human culture model (Nikitin et al., 2001) have demonstrated that the induction of an anti-p53 CTL cell response has selectively killed tumor cells and spare normal cells. Furthermore, anti-p53 T cells have been shown to be present in cancer patients (Hoffmann et al., 2005; Sirianni et al., 2004; van der Burg et al., 2003).
Another critical element of cancer vaccines is a selection of adequate carrier for TAA. This vehicle should help to activate the primary immune response and if necessary to overcome tolerance to self-proteins. Dendritic cells (DC) are most potent antigen presenting cells and are actively used in cancer immunotherapy (reviewed in Gabrilovich, 2002). In recent years it became increasingly clear that success of DC-based immunotherapy depends of activation status of these cells. Adenovirus provides one exemplary effective means to activate DCs. It induced up-regulation of MHC class II and co-stimulatory molecules on DC surface, production of IL-12, Th1, and pro-inflammatory cytokines (Nikitina et al., 2002; Tan et al., 2005; Herrera et al., 2002). Adenovirus also provides excellent tool for gene delivery into DCs (reviewed in Humrich and Jenne, 2003; Gamvrellis et al., 2004).
WO 00/54839 describes dendritic cells transduced with a wild-type self gene for the treatment of hyperproliferative disease.
Despite the foregoing, there currently exist no methods of self gene-based immunotherapy capable of utilizing wild-type self genes to generate an antitumor immune response specific for a variety of therapy-resistant cells overexpressing different mutant self proteins. This would permit the treatment of any cancerous or pre-cancerous cell associated with increased or altered expression of the self gene. Further, it would eliminate the need to identify the site of self gene mutation in each patient and generate customized self gene mutant peptides for immunotherapy. Thus, the need exists for an immunotherapy that is capable of attenuating or enhancing the natural immune systems CTL response against hyperproliferative cells with increased or altered expression of mutant self gene antigens.